Das, Sananda and Sahoo, R C and Mishra, Shubhankar and Bhattacharya, Dipten and Nath, T K (2022) Effects of Ni doping at Co-site on dielectric, impedance spectroscopy and AC-conductivity in La2CoMnO6 double perovskites. Applied Physics A-Materials Science & Processing, 128 (4). Art No-354. ISSN 0947-8396

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Multifunctionalities of double perovskites depend strictly on the 3d/4d/5d-transition metals that can be purposefully tuned by doping effect at the transition metal-site. In the present study, the effects of Ni doping at the Co-site on the dielectric, magnetodielectric, complex impedance, complex modulus and ac-conductivity are investigated in detail for the La2Co1-xNixMnO6 (x = 0, 0.1, 0.5) double perovskites. At room temperature, all the compounds exhibited monoclinic crystal symmetry (space group P2(1)/n). No structural phase transition and/or impurity phases were observed after doping. The dielectric behavior is investigated over a wide frequency (100-1 MHz) and temperature (100-300 K) ranges, revealing an enhancement in the dielectric constant for the doped samples compared to parent La2CoMnO6. The magnetodielectric effect is also observed for x = 0 and x = 0.1 samples under 3 T magnetic field. The contributions of grain and grain boundaries at high and low frequencies become evident from the complex impedance spectroscopic and modulus studies. The corresponding carrier activation energies for all the samples are estimated from the Arrhenius fittings. The Nyquist plots are fitted well with an equivalent circuit consisting of two parallel resistance-capacitance elements connected in series, representing the grain and grain boundary effects. The behaviour of the temperature-dependent unitless exponent function predicts the Overlapping Large Polaron Tunneling mechanism in the parent system, while the non-overlapping Small Polaron Tunneling model best describes the doped x = 0.5 system. We confirmed by dc-conductivity study that the samples exhibited semiconductor-like nature in a wide temperature range. By revealing the dielectric, impedance and conductivity behaviours of Ni-doped La2CoMnO6, our study broadens the scope of further research on the doping effect at transition metal-sites in perovskites.

Item Type: Article
Subjects: Electronics
Depositing User: Bidhan Chaudhuri
Date Deposited: 29 Aug 2023 10:25
Last Modified: 29 Aug 2023 10:25
URI: http://cgcri.csircentral.net/id/eprint/5439

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